Lead type printing block.
This is a block of type meant for printing report cards for a small school district in a rural area near where I live. I got it at the closing out auction of a small school-supplies printer in a small town. If you look on eBay these days (2007) you'll see hundreds of items like this for sale: Small printers are going out of business left and right. I think most of them are already gone, it's only a few stragglers in small towns and rural areas that have lasted this long. They are being replaced by more efficient, larger operations that were able to keep up with technology. The one I got this item from looked like it had not updated its printing process since the 1950's.
This block represents the oldest lead-type printing technology: Each letter is on an individual block of lead, with lines of type assembled by hand, one letter at a time, with "leading", made of actual lead, in between lines to provide spacing.
Here's a picture that has been mirrored horizontally so you can read what it says (the actual printing block, as seen in the main sample image, is of course mirror-reversed, so the text will come out right when applied to paper):